This invention is an improvement on Krayer U.S. Pat. No. 5,152,592, which discloses the use of a 4:3 hypocycloid rotation guide for rotating a shelf in the shape of a Reuleaux triangle. FIGS. 5A to 5H of the '592 patent illustrate that the rotation of a Reuleaux triangle-shaped shelf in a square area can be adapted to the floor or shelf of a corner cabinet such as a standard corner kitchen cabinet in a generally square shape. During the rotation, the shelf follows closely all four sides of the square area at all times, the apexes of the Reuleaux triangle describing the substantially square area as they rotate, and results in alternate recessed and projecting modes when used in a corner cabinet having a 45° face. The kinematics of such a rotation permits various types of guides such as are shown in FIGS. 6–13 and 17–19 of the U.S. Pat. No 5,152,592 patent. The entire patent U.S. Pat. No. 5,152,592 is incorporated herein by reference.
If a Reuleaux triangle is caused to turn in a full square precisely as disclosed in FIGS. 5A to 5H of U.S. Pat. No. 5,152,592, the discerning experimenter will observe that the path of the center of the Reuleaux triangle is not exactly a true circle; rather, it comprises four elliptical curves. Nevertheless, the path is close enough to circular that a shelf guide based on circular motion is quite practical.
While the turntable or shelf disclosed by Krayer in U.S. Pat. No. 5,152,592 is appealing in many respects, the original guide system in practice entailed the use of ball casters in a groove such as depicted in FIG. 7. The ball casters were noisy and their durability was suspect.
This invention is also an improvement on Gerkey and Kugler U.S. Pat. No. 6,568,772, which describes the use of substantially planar bearings for a shelf or turntable in the shape of a Reuleaux triangle. U.S. Pat. No. 6,568,772 is also incorporated herein by reference in its entirety.
While the planar bearings of the Gerkey and Kugler disclosure are an excellent improvement on the ball casters disclosed in Krayer U.S. Pat. No. 5,152,592, the guide groove and vertical-axis rollers proposed by Gerkey and Kugler to guide the rotation of the shelf save little in terms of expense compared to my earlier proposed ball casters and groove. Accordingly, a different application of the hypocycloid principle is needed in the art of rotatable shelves.
The reader may be interested in reviewing some or all of the patents mentioned in this paragraph. The term “gerotor,” used in the present disclosure and claims, may be found, for example, in Hanson U.S. Pat. No. 4,519,755 and Whitham U.S. Pat. No. 5,762,484. Illustrations of various internal gear-like mechanisms having ratios other than 4:3 may be seen in the following U.S. Patents: Grant U.S. Pat. No. 3,304,808, Sundy U.S. Pat. No. 2,874,594, Hill U.S. Pat. No. 2,209,201, Dorff et al U.S. Pat. No. 3,834,842, Godines U.S. Pat. No. 3,779,521, Meaden U.S. Pat. No. 3,913,533, Geralde U.S. Pat. No. 5,820,504, and Hoffmann U.S. Pat. No. 5,046,932. The term “Reuleaux triangle” appears recently in Gagnon et U.S. Pat. No. 6,552,349; see also Morrell et al U.S. Pat. No. 4,074,778, and Roepke et al U.S. Pat. Nos. 4,012,077 and 4,062,595. Many turning supports such as swivels for various turntable-like elements have been suggested—see, for example, U.S. Pat. No. 2,062,807 to Cramer, U.S. Pat. No. 2,648,579 to Slyter et al, U.S. Pat. No. 5,701,694 to Atkinson, and U.S. Pat. No. 1,628,013 to Twedt.